IMHO..
I think the Goliath ll has a more focused sound than the lll. The front port on the lll spreads out the sound where the ll with the port in the rear shot the sound out like a cannon...
I hope this was helpful and made some sense??
They are both great cabs... I still have the lll and I like it...

Having played a Gol I, II, and III, I have to say that the I and III are awesome but the II just didn't keep up. I would give more info on the sound but I really cannot remember much more than my prefrence; my comparison was a while back when a local GC had the III new and the I and II used.